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Menampilkan postingan dari April, 2008

More Liver

It's time to celebrate your liver. It's a hard-working organ and it deserves some credit.

One of the liver's most important overall functions is maintaining nutrient homeostasis. It controls the blood level of a number of macro- and micronutrients, and attempts to keep them all at optimal levels.

Here's a list of some of the liver's functions I'm aware of:
Buffers blood glucose by taking it up or releasing it when neededA major storage site for glycogen (a glucose polymer)
Clears insulin from the bloodSynthesizes triglyceridesSecretes and absorbs lipoprotein particles ("cholesterol")Stores important vitamins: B12, folate, A, D, E, K (that's why it's so nutritious to eat!)Stores minerals: copper and iron
Detoxifies the bloodProduces ketone bodies when glucose is running lowSecretes blood proteinsSecretes bileConverts thyroid hormonesConverts vitamin D (D3 --> 25(OH)D3)
The liver is an all-purpose metabolic powerhouse and storage depot. In the n…

The Liver: Your Metabolic Gatekeeper

As I've been learning more about the different blood markers of metabolic dysfunction, something suddenly occurred to me. Most of them reflect liver function! Elevated fasting glucose, low HDL cholesterol, high LDL cholesterol, high triglycerides and high fasting insulin all reflect (at least in part) liver function. The liver is the "Grand Central Station" of cholesterol and fatty acid metabolism, to quote Philip A. Wood from How Fat Works. It's also critical for insulin and glucose control, as I'll explain shortly. When we look at our blood lipid profile, fasting glucose, or insulin, what we're seeing is largely a snapshot of our liver function. Does no one talk about this or am I just late to the party here?!

I read a paper today from the lab of C. Ronald Kahn that really drove home the point. They created a liver-specific insulin receptor knockout (LIRKO) mouse, which is a model of severe insulin resistance in the liver. The mouse ends up develop…

Book Review: Blood Sugar 101

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I just finished reading "Blood Sugar 101" by Jenny Ruhl. It's a quick read, and very informative. Ruhl is a diabetic who has taken treatment into her own hands, using the scientific literature and her blood glucose monitor to understand blood sugar control and its relationship to health. The book challenges some commonly held ideas about diabetes, such as the notion that diabetics always deteriorate.

She begins by explaining in detail how blood glucose is controlled by the body. The pancreas releases basal amounts of insulin to make glucose available to tissues between meals. It also releases insulin in response to carbohydrate intake (primarily) in two bursts, phase I and phase II. Phase I is a rapid response that causes tissues to absorb most of the glucose from a meal, and is released in proportion to the amount of carbohydrate in preceding meals. Phase II cleans up what's left.

In a person with a healthy pancreas, insulin secretion will keep blood glucose u…

Olive Oil Buyer's Guide

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Olive oil is one of the few good vegetable oils. It is about 10% omega-6 (n-6) fatty acids, compared to 50% for soybean oil, 52% for cottonseed oil and 54% for corn oil. Omega-6 fatty acids made up a smaller proportion of calories before modern times, due to their scarcity in animal fats. Beef suet is 2% n-6, butter is 3% and lard is 10%. Many people believe that excess n-6 fat is a contributing factor to chronic disease, due to its effect on inflammatory prostaglandins. I'm reserving my opinion on n-6 fats until I see more data, but I do think it's worth noting the association of increased vegetable oil consumption with declining health in the US.

Olive oil is also one of the few oils that require no harsh processing to extract. As a matter of fact, all you have to do is squeeze the olives and collect the oil. Other oils that can be extracted with minimal processing are red palm oil (9% n-6), hazelnut oil (10% n-6) and coconut oil (2% n-6). These are also the oils I …

Real Food V: Sauerkraut

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Sauerkraut is part of a tradition of fermented foods that reaches far into human prehistory. Fermentation is a means of preserving food while also increasing its nutritional value. It increases digestibility and provides us with beneficial bacteria, especially those that produce lactic acid. Raw sauerkraut is a potent digestive aid, probably the reason it's traditionally eaten with heavy food.

Sauerkraut is produced by a process called ‘anaerobic’ fermentation, meaning ‘without oxygen’. It’s very simple to achieve in practice. You simply submerge the cabbage in a brine of its own juices and allow the naturally present bacteria to break down the sugars it contains. The process of ‘lacto-fermentation’ converts the sugars to lactic acid, making it tart. The combination of salt, anaerobic conditions, and acidity makes it very difficult for anything to survive besides the beneficial bacteria, so contamination is rare. If it does become contaminated, your nose will tell you as soon as…

Leptin

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I've been puzzled by an interesting question lately. Why is it that certain cultures are able to eat large amounts of carbohydrate and remain healthy, while others suffer from overweight and disease? How do the pre-industrial Kuna and Kitavans maintain their insulin sensitivity while their bodies are being bombarded by an amount of carbohydrate that makes the average American look like a bowling ball?

I read a very interesting post on the Modern Forager yesterday that sent me on a nerd safari through the scientific literature. The paper that inspired the Modern Forager post is a review by Dr. Staffan Lindeberg. In it, he attempts to draw a link between compounds called lectins, found in grains (among other things), and resistance to the hormone leptin. Let's take a step back and go over some background.

One of the most-studied animal models of obesity is called the "Zucker" rat. This rat has a missense mutation in its leptin receptor gene, causing it to be nonfun…

Hydration: Attempt Only Under Medical Supervision

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I've noticed how the word "hydration" has crept into the popular lexicon in the last decade or so. Before that, we were so primitive, we just "drank water". Now you need a PhD just to put a glass to your lips. I'm not sure I'm qualified!

I've been hearing so many people, including health professionals, tell me to drink 8 glasses of water a day for my entire life. In my middle school health class, I was told by my hydrophilic teacher that I should be urinating every hour and my urine should always be clear. For my whole life, I've thought it was nonsense. Yet the message has reached people. Walk around any college campus and you'll see undergrads faithfully carrying around their endocrine-disrupting plastic-water everywhere they go.

You see, our bodies have this very sophisticated mechanism to ensure water homeostasis. It's called thirst. If we need so much water to be healthy, why aren't we thirsty more often?

I skimmed throu…

Low-carb Review Article

The other day, I came across this nice review article from the American Journal of Clinical Nutrition. It gives a thorough but accessible overview of the current state of research into carbohydrate-restricted diets, without all the fatophobic mumbo-jumbo. It points out a few "elephants in the room" that the mainstream likes to ignore. First of all, the current approach isn't working:
The persistence of an epidemic of obesity and type 2 diabetessuggests that new nutritional strategies are needed if the epidemicis to be overcome.They claim that preagricultural diets were low in carbohydrate:
In contrast to current Western diets, the traditional dietsof many preagricultural peoples were relatively low in carbohydrate(1, 2). In North America, for example, the traditional dietof many First Nations peoples of Canada before European migrationcomprised fish, meat, wild plants, and berries. The change inlifestyle of several North American aboriginal populations occurredas recent…